Search for most stable structure of Si8H8 cluster

We have performed a global structure optimization for Si8H8 cluster using a genetic algorithm (GA) coupled with an efficient and accurate tight-binding (TB) potential to describe the energies of the clusters. Structure models selected from the GA/TB optimization are further verified by ab initio calculations. Our study shows that a new structure with C2 symmetry is energetically more stable than the octasilacubane structure previously proposed for Si8H8. This is in contrast to Ge8H8 where the octasilacubane structure is energetically more stable than the new C2 structure. Vibration and electronic properties of the new Si8H8 structure have also been studied.